This invention relates to a torque divider for distributing the engine torque in a determined torque dividing ratio and, in particular, to a torque divider employed in a center differential limiting device which serves to distribute the engine torque to the front wheels and the rear wheels in a four wheel drive motor vehicle.
The German Patent Application No. P 39 06 650.9 (the Japanese Patent Application Laid Open No. 2-266142) discloses a conventional torque divider 201 as shown in FIG. 1. This torque divider 201 includes a pair of pinion gears 205, 207 which are housed inside and supported by a differential-gear case 203, and a pair of side gears 209, 211 which are connected to front and rear axle shafts, respectively. The pair of pinion gears 205, 207 mesh with each other. The side gear 209 is meshed with the pinion gear 205, and the side gear 211 is meshed with the pinion gear 207.
The torque of the engine which rotatively drives the differential-gear case 203 is distributed to each front and rear axle shaft through the pinion gears 205, 207 and the side gears 209, 211. The number of gear teeth of the side gear 211 (N2) is greater than that of the side gear 209 (N1). Accordingly, the torque dividing ratio between the side gears 209, 211 is N1:N2. Thus, when this mechanism is employed in the center differential limiting device of a four wheel drive motor vehicle, it is possible to distribute a greater proportion of the total torque to the rear axle shaft than to the front axle shaft.
However, if the radius of the side gear 211 is enlarged to enhance the torque dividing ratio, the radial size of the torque divider 201 also becomes larger. Meanwhile, the limiting factor of the size of the radius of the shaft around which the side gear 209 is secured, deters decreasing the radius of the side gear 209 to enhance the torque dividing ratio in the torque divider 201. Accordingly, it is difficult to enhance the torque dividing ratio in the torque divider 201. Further, since the pinion gears 205, 207 are meshed with the side gears 209, 211 at the inner radial side thereof, it is necessary to fill the space between the side gear 209 and the side gear 211 with a filling member 213 so that the member 213 can receive the thrust force generated in the meshing of the gears 205, 207, 209, 211.